Rotational forming of thin SS316L sheets

Bipolar half plates (BPPs) are important parts of Proton Exchange Membrane (PEM) hydrogen fuel cells. Metallic BPPs are generally produced by stamping or hydro forming. However, these processes are not continuous and relatively slow compared to rotary forming. Rotary forming is a continuous process and could potentially be a faster BPP...

Shape and size optimization of a wind turbine transport structure: Structural optimization with a compliant ship foundation

Due to the growing quest for renewable energy, wind turbines grow in size. This means that higher demands are posed on the transporting structures, also called tower grillages, which brings its challenges for their design. The fact that the structures considered in this thesis are placed on a ship makes the design even more complicated....

Impact resistance of ship hull to berthing loads: quantifying critical fender impact

Over the last two decades, the size and capacity of (container) vessels calling port at the Port of Rotterdam have increased considerably. To moor these huge and heavy ships safely at the quay, fenders are frequently installed. The present guidelines for the “Design of Fender Systems”, which were established in 2002, are due to be updated in...

Experimental and numerical investigation on the crush behavior of composite Formula One structures

The state-of-the-art design approach of composite structures in Formula One (F1) rely on expensive full-scale crash tests and simple models that cannot describe the underlying physical phenomena during crushing. Although the models can describe the crush forces and resulting accelerations, their predictive capabilities are poor, and several...

Measuring stress-strain behavior of mild steel at intermediate strain rates

Impacts on offshore installations and ships can cause strains at high rates. It is known that mild steel lower yield stress and hardening are strain rate dependent. Measuring this material behavior is not easy, as test results from many researchers, show heavy vibration. Vibration is normally referred to as ringing. This...

Load Capacity of Low Speed Steel Wheels

Steel wheels are often essential parts for heavy construction equipment, such as constructed by Huisman. These steel wheels must endure heavy loads. In order to prevent downtime, costs and to guarantee safety, it is important that the steel wheels do not fail. One important failure mode is failure resulting from subsurface initiated cracks. This...

Allowable Hull Loading due to Fender Contact

Marine structures are frequently equipped with rubber fender systems, which absorb the berthing en­ergy in order to protect both the marine structure and the berthing vessel. These fender systems absorb the kinetic berthing energy by elastic deflection and the associated reaction fender force introduces a berthing impact load acting on the...

Topology optimization for ship structures with manufacturing constraints

Currently, most ships are designed on the basis of rules and reference ships for which often only the critical structural parts are calculated and designed in detail. This process can result in an over-dimensioned ship with the standard structural outcome of longitudinal stiffeners, transverse stiffeners, and bulkheads with a fixed distance due...

The effect of the yield to tensile strength ratio on the stress field in stress/strain concentrations around holes in steel structures

The aim of this thesis is to determine the influence of the Y/T, yield to tensile strength, ratio on the stress fields of high strength steels. This is relevant to the offshore industry as regulations restrict the use of steels with a high yield to tensile strength ratio, which is a characteristic of high­-strength and<br/>ultra high­-strength...

Analytical description of the forming process of a double curvature shipbuilding plate

The forming of double curvature shipbuilding steel plates is performed by experienced craftsmen at IHC Metalix. Their experience will get lost when they retire; therefore, it can be valuable for future metal workers to capture the forming process of a double curved plate theoretically. An analytical description and understanding of the forming...

Design guide for stress-strain measurements of strain rate sensitive metals using impact experiments and DIC

Strain rate, how fast a material is strained, is known to have an effect on the behaviour of metals. Being able to measure the effect of strain rate in a material provides more reliable material data as input for material models. Strain rates up to 10 per second can be tested using a (fast) hydraulic testing machine. Strain rates upwards from...

Cleavage fracture during multiaxial loading: identifying stress parameters in ferritic steels

Brittle fracture in ferritic steels is a field in which a lot of research has been performed over the years. Most of this research has been done on uniaxially loaded specimens, such as single edge notched bend specimens. From these experiments, the maximum principal stress criterion is used in the Weibull distribution method as proposed by...

Stress State Dependent Fracture Prediction in Shells

The goal of this thesis is to propose a stress state dependent ductile fracture criterion for shell elements that can be used for crash simulations for example collisions of ships with offshore structures. Fracture has been extensively researched for solid elements for finite element analysis in Bai &amp; Wierzbicki [2009], among others. Shells...

Preventing Injuries of High Speed Marine Craft Operators: Incorporating Spinal Injury Models in the Analyses of Various Seat Suspension Principles

On board of High Speed marine Craft (HSC), the crew and the passengers are exposed to high levels of Whole Body Vibrations (WBV) and large magnitude Repeated mechanical Shocks (RS) caused by the motions of the craft. The HSCs are typically 10 meters long, capable of reaching a maximum speed up to 50 knots and widely used by various maritime...

Assessing the susceptibility of existing pipelines to Hydrogen Embrittlement: A combined modelling and in-situ experimental approach

With fossil fuels being phased out and growing global interest in a hydrogen economy, there is demand for re-purposing existing pipelines for transportation of hydrogen gas. However, hydrogen is known to have adverse affects on the properties of steels. Hydrogen will dissolve in the steel matrix and contribute to a reduction of mechanical...

Predicting Buckling and Plasticity of Finite Element Models Using Machine Learning: An Application of Convolutional Neural Networks on the Ultimate Strength and Stress Distribution Prediction of Stiffened Panels

The ongoing demand for bigger and more efficient ships pushes their designs towards the strength limits. Sometimes, ship structures are pushed beyond their limits with the possibility of significant negative economic and environmental impact or, in the worst case, impact on human life. This makes it explicitly clear why the development of...

Analytical model to assess bending moments in wind turbine support structures subjected to ship collisions

The number of offshore wind farms is growing rapidly, which increases the likelihood of ship collisions with offshore wind turbines. Additionally, the cost of energy reduction for wind turbines is achieved due to radical design optimizations. Therefore, simple methods should be obtained to determine the offshore wind turbine response during ship...

Prognostics-driven supply chain optimization in commercial aviation

Maintenance providers in commercial aviation are looking into new strategies to improve maintenance operations and aircraft availability in order to reduce cost and increase customer satisfaction. Aircraft availability and thus profitability highly relies on adequate maintenance because an aircraft is only profitable when...